Depends highly on what job you want to play. Maybe 60 or so hours for a faster job (mage). http://royals.ms/forum/threads/catlaunchs-training-guide.12021/
I can tell you that 1-30 on a mage took me 3 hours starting from scratch while adding mpgain before magicclaw.
Getting to 120 isn't too bad if you don't mind the monotonous grind. After 75, you could probably get to 120 in 15 hours if you have leech.
I got from 72 to 98 in a day. Bombing BFs is too good. I don't know, though. The first hours of grinding were terror for me, up to Lv. 70. Maybe 90-100 hours of actual training.
